Abstract:To investigate the fermentation process of Lacticaseibacillus paracasei SMR-0128 and its effects on intestinal motility，the fermentation culture conditions of Lacticaseibacillus paracasei SMR-0128 were optimized by single-factor experiments and response surface methodology （RSM），and its effects on the intestinemoistening and laxative functions of mice were analyzed using an animal constipation model. The optimal fermentation conditions were determined as follows：liquid volume of 140 mL/250 mL，inoculum amount of 4%，seed age of 12 h，rotation speed of 74 r/min，initial pH value of 7，and culture at 36 ℃ for 25 h. Under these conditions，the biomass reached 3.22×1010 CFU/mL，which was 12.5 times higher than that before optimization.The experimental animals were administered Lacticaseibacillus paracasei SMR-0128 at daily doses of 1× 109 CFU/kg bw and 1×108 CFU/kg bw. Compared with the control group，the small intestinal propulsion rates of mice in the experimental groups were significantly increased，and the time to the first black stool defecation was significantly shortened，indicating that Lacticaseibacillus paracasei SMR-0128 possessed good intestinemoistening and laxative functions.